Operating mechanism for enclosed circuit interrupter



y 4, 1963 J. o. REXROAD 3,089,928

OPERATING MECHANISM FOR ENCLOSED CIRCUIT INTERRUPTER Filed Jan. 19, 19602 Sheets-Sheet 1 III] 1111/! IIIII IIIII IIIII'I III III 32 El f raw' fiCOVER -OPEN WITNESSES INVENTOR James O. Rexrood V Y W ATTORNEY y 4, 1963J. o. REXROAD 3,089,928

OPERATING MECHANISM FOR ENCLOSED CIRCUIT INTERRUPTER Filed Jan. 19, 19602 Sheets-Sheet 2 Fig.2.

Fig.3.

United States Patent G 3,089,923 OPERATING MECHANifiM FOR ENCLOSED ClRCUIT INTERRUPTER James 0. Rexroad, Beaver, Pa., assignor to WestinghouseElectric Corporation, East Pittsburgh, Pa., :1 corporation ofPennsylvania Filed Jan. .19, 1960, Ser. No. 3,375 10 Claims. (Cl.filth-d) This invention relates, generally, to circuit interrupters and,more particularly, to operating mechanisms for circuit interrupterswhich are mounted inside enclosing cabinets having an operating handlemounted on the outside of the cabinet.

As explained in my copending application, Serial No. 797,131, filedMarch 4, 1959, now Patent No. 3,054,886, operating conditions in certainmodern industrial plants make it desirable to provide safety features onenclosed circuit interr-upters in addition to the safety featurespreviously considered necessary. The operating mechanism and safetyfeatures described in the aforesaid application are suitable forutilization with cabinets which are rela tively long and narrow with theexternal operating handle located at the top of the cabinet. However,when such cabinets are installed in certain switchboard structures, theoperating handle is above the maximum permissible height.

An object of this invention is to provide an enclosed circuitinterrupter having an external operating handle located at the side ofthe enclosing cabinet, but extending in front of the cabinet.

Another object of the invention is to provide an enclosed circuitinterrupter having an external operating handle mechanically connectedto the operating member of the interrupter at all times regardless ofthe position of the cabinet cover.

A further object of the invention is to provide for locking theinterrupter in the off position with the cover either open or closed.

Still another object of the invention is to provide a voidable interlockfor normally preventing the closing of the interrupter while the coveris open.

A still further object of the invention is to provide .an operatingmechanism which can be utilized with cabinets of different depths forenclosing a circuit interrupter.

Yet another object of the invention is to provide a cover latchingmechanism which prevents the cover from being left in a partly closedposition.

A further object of the invention is to provide a cover latchingmechanism which requires a separate tool in addition to the latchinghandle in order to open the cover.

Other objects of the invention will be explained fully hereinafter orwill be apparent to those skilled in the art.

In accordance with one embodiment of the invention, the externaloperating handle for an enclosed circuit interrupter is mounted on afixed portion of the cabinet at one side of the front of the cabinet andis connected to the interrupter regardless of the position of the cover.Mechanical interlocking prevents the closing of the interrupter unlessthe cover is fully closed by a cover latching mechanism, except that theinterlock can be deliberately voided. A separate tool is required toopen the cover, which can be locked in the closed position. Theinterrupter can be locked 01f regardless of the position of the cover.

For a better understanding of the nature and objects of the invention,reference may be had to the following detailed description, taken inconjunction with the accompanying drawings, in which:

FiGURE 1 is a View, partly in front elevation and partly in section, ofa portion of a cabinet and a mechanism for operating a circuitinterrupter mounted inside the cabinet;

FIG. 2 is a view, partly in side elevation and partly in section, of thestructure shown in FIG. 1;

FIG. 3 is a view, in section, of the cover latching mechanism, takenalong the line LII-III in FIG. 2; and,

FIG. 4 is an enlarged view, in section, of the interlocking mechanism.

Referring to the drawings, and particularly to FIGS. 1 and 2, thestructure shown therein comprises a portion of a sheet metal cabinet 11of dust tight or liquid tight construction inside of which a circuitinterrupter 12, an operating mechanism 13 and a cover latching mechanism14- are mounted. It will be understood that additional controlapparatus, such as a motor starter, may be mounted in the cabinet 11 ifdesired.

As shown, the front wall of the cabinet 11 comprises a fixed portion 16and an openable cover 17. The fixed portion 16 of the front wall may beformed as an integral part of the cabinet 11 and it extends along oneside of the front of the cabinet at a lower level than it would extendif it were disposed at the top of the front (i.e. the uppermost part asviewed in the plane of the paper in FIG. 1) of the cabinet. The cover ordoor 17 may be hinged to the cabinet by means of a plurality of hinges(not shown). The cabinet 11 may be mounted on a vertical panel or othersupporting member in any suitable manner. A gasket 18 is providedbetween the cover .17 and the walls of the cabinet 11 to exclude dustand other foreign matter from the inside of the cabinet.

An external operating handle 21 is pivotally mounted on the fixedportion 16 at one side of the cabinet. The handle 21 is supported by apin 22 disposed in a frame 23 mounted on top of the fixed portion 16 ofthe cabinet 11. The handle 21 has two oppositely extending arms 24 and25 which engage push rods 26 and 27 respectively, which extend insidethe cabinet 11 through bushing portions 28 formed in the base of theframe 23. The frame 23 may be molded from a suitable insulatingmaterial. An indexing pin 29 may be provided in the handle 21 toidentify more clearly the on, off, etc. positions of the handle.

A generally U-shaped operating lever 31 is pivotally mounted inside thecabinet 11. The legs of the U-shaped lever 31 may be attached to theside walls of the cabinet .11 by pins 32. As shown most clearly in FIG.2, a cross arm 33 is secured to one leg of the lever 31. One end of thecross arm 33 is connected to the push rod 26 by a connecting link 34.The other end of the arm 33 is connected to the push rod 27 by anotherlink 34. The links 34 are threaded onto the push rods, therebypermitting the effective length of the push rods to be properlyadjusted.

The circuit interrupter 12 may be a manually operable switch of the typedescribed in Patent 2,849,572, issued August 26, 1958 to A. R. Celleriniet al. As described in the aforesaid patent, contact members of theswitch are opened and closed by a toggle mechanism which is actuated byan oscillating operating member 35. If desired, the circuit interrupter12 may be a circuit breaker of the type described in Patent 2,047,739,issued July 14, 1936 to H. J. Lingal. The contact members of the circuitbreaker may be manually opened or closed by oscillatory movement of anoperating member similar to the member 35. The circuit breaker may beprovided with a tripping mechanism which is operable in response topredetermined overload currents to effect automatic.

opening of the contact members.

As shown in FIG. 1, the operating member 35 of the interrupter 12extends through an opening in the lever 31. As explained hereinbefore,the arms of the operating handle 21 engage the push rods 26 and 27 whichare connected to the cross arm 33 of the operating lever 31. Thus, theoperating handle 2]. is continuously connected to the operating member35 of the interrupter 12, so that it is impossible to move theinterrupter Opel ating member if the external operating handle 21 islocked. This is true even though the door of the cabinet may be opened.The operating handle 21 may be locked in the off position by insertingthe hasp of a padlock in an opening 36 in the arm 25 of the handle 21.The hasp of the padlock will engage sides 37 of the frame 23 to retainthe handle 21 in the off position.

The latching mechanism 14 is provided to force the door or cover 17 tothe fully closed and sealed position. An interlocking mechanism 41cooperates with the latching mechanism to insure that the interruptercan normally be operated only when the cover is in the fully closedposition. As shown most clearly in FIGS. 2 and 3, the latching mechanism14 comprises a cover closing handle 42 and a spring biased lever 43. Thehandle 42 is pivotally mounted on a pin 44 which extends through sides45 of the frame 23. The lever 43 is pivotally mounted on a pin 46 whichextends through spaced arms of a generally U-shaped bracket 47 attachedto a side wall of the cabinet 11.

As shown in FIG. 3, the lever 43 has a cam shaped hook portion 48 whichengages a bracket 44 attached to the cover 17 to draw or force the cover17 to its fully closed position to compress the gasket 18. The lever 43is biased in a direction to release the cover 17 by a spring 51. Thelever '43 is actuated in a direction to close the cover 17 by means ofthe handle 42 which has a cam shaped portion 52 engaging a push rod 53.The rod 53 engages an arm 54 of the lever 43 to actuate the lever aboutits pivot point 46 to engage the bracket 44 on the cover 17.

If it is desired to open the cover 17, the handle 42 must be movedcounterclockwise as shown in FIG. 2. However, before the handle 42 canbe moved counterclockwise, it is necessary to release the interlockingmechanism 41. The interlocking mechanism 41 comprises two spring biasedinterlocking members 55 and 56 which are slidably disposed in the frame23. The member 55 is biased towards the left as shown in FIG. 2 by aspring 57. The member 56 is biased towards the right by a spring 58. Thespring 57 is stronger than the spring 58 and a pin 59 carried by themember 55' engages the member 56 to move it toward the left Whereupon aprojection 61 on the member 55 is disposed in a notch 62 in the camshaped portion 52 of the handle '42. When the member 56 is in itsfurthermost position toward the left, a projection 63 on the member 56will clear the end of the arm 24 on the operating handle 21. Thus, thecircuit interrupter 12 can be opened and closed by means of the handle21 when the cover 17 is in its fully closed position.

In order to open the cover 17, a screwdriver, or other tool, must beinserted through an opening in the frame 23 into a recess 64 in theinterlocking member 55 and the member 55 moved towards the right todisengage the projection 61 from the cam 52 of the handle 42. The handle42 is then moved counterclockwise, thereby permitting the spring 51 todisengage the lever 43 from the cover 17.

The cam 52 will retain the member 55 in its right hand position whilethe cover 17 is open. When the member 55 is in its right hand position,the member 56 is actuated towards the right by the spring 58, therebycausing the projection 63 to interfere with the arm 24 on the handle 21to prevent the closing of the circuit interrupter while the cover isopened. However, the interlock can be voided or defeated by moving themember 56 towards the left by means of the handle portion 65. The uppersurface of the projection 63 and the lower surface of the arm 24 are sosloped that the interrupter can be thrown off when the cover is openwithout utilizing a tool to release the interlock. The sloping surfacesproduce a carnming action to move the member 56 towards the left.

The cover 17 can be locked in the closed position by inserting the haspof a padlock into an opening 66 in the handle 42 and sides 45 of theframe 23. The hasp of the padlock will engage the sides 45 of the frame23 to prevent movement of the handle 42 in a direction to release thecover 17.

From the foregoing description, it is apparent that the improvedoperating and the interlocking mechanisms occupy a relatively smallamount of space at one side of the front of the cabinet on a fixed frontportion of the cabinet. Thus, the handle can be positioned within easyreach of an individual of average height when the cabinet is installedin a switchboard structure. Since the operating handle moves in a planethat is generally normal to the plane defined by the front of the closedcover, adequate leverage is provided without having the handle extendpast the front-elevational-view dimensions of the enclosure while thewidthwise dimension of the fixed front stationary part of the enclosurecan be kept relatively small so that the opening provided in theenclosure can be relatively large. Furthermore, the operating mechanismcan be utilized with cabinets of different depths by providing push rodsof different lengths. Thus, the mechanism can be utilized with differentenclosures and still provide the safety features required by certainindustries.

Since numerous changes may be made in the abovedescribed construction,and different embodiments of the invention may be made Without departingfrom the spirit and scope thereof, it is intended that all mattercontained in the foregoing description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

I claim as my invention:

1. In combination, an enclosure comprising a cabinet the front of whichis defined as having a top a bottom and two sides, a fixed front portionat one side of the front of said cabinet, an openable cover positionedat the front of said cabinet, a circuit interrupter mounted inside ofsaid enclosure and having an operating member operable to open and closesaid interrupter, an external operating handle extending from said fixedfront portion, means operatively connecting said external operatinghandle to said operating member in such a manner that said operativeconnection is maintained regardless of the position of said cover, acover latching mechanism compris ing manually operable cam meansoperable from outside of said enclosure and being operable from anunlatching position to a latching position to cam said cover to a fullyclosed latched position, interlocking means operating to prevent closingof said circuit interrupter when said circuit interrupter is open andsaid manually operable cam means is moved from said latching position tosaid unlatching position to permit opening of said cover, saidinterlocking means engaging said manually operable cam means to preventopening of said cover when said cover is in said fully closed latchedposition and said manually operable cam means is in said latchingposition, means operable from outside of said enclosure when saidmanually operable cam means is in said latching position and said coveris in said fully closed position to defeat said interlocking means topermit opening of said cover.

2. In combination, an enclosure comprising a cabinet the front of whichcomprises a top a bottom and two sides, said cabinet having a fixedfront portion at one side of the front thereof, an openable coverpositioned at the front of said cabinet, a circuit interrupter mountedinside of said enclosure and having an operating member operable to openand close said interrupter, an external operating handle extending fromsaid fixed front portion and being movable in a plane that is generallynormal to the plane defined by the front of said cover when said coveris in a fully closed position, means operatively connecting saidexternal operating handle to said operating member in such a manner thatsaid operative connection is maintained regardless of the position ofsaid cover, a cover latching mechanism comprising manually operable cammeans operable from outside of said enclosure from a first position to asecond position to cam said cover to the fully closed position,interlocking means, said manually operable cammeans being movable fromsaid second position to said first position to permit opening of saidcover during which movement said interlocking means is operated toprevent a closing operation of said external operating handle, and meansoperable when said manually operable cam means is in said first positionto defeat said interlocking means to permit a closing operation of saidoperating handle.

3. In combination, an enclosure comprising a cabinet having a fixedportion at the front thereof, an openable cover positioned at the frontof said cabinet, a circuit interrupter mounted inside of said enclosureand having an operating member operable to open and close saidinterrupter, an external operating handle extending from said fixedportion and being movable in a plane generally normal to the planedefined by the front of said cover when said cover is in a fully closedposition, means operatively connecting said external operating handle tosaid operating member in such a manner that said operative connection ismaintained regardless of the position of said cover, a cover latchingmechanism comprising manually operable carn means operable from outsideof said enclosure from a first position to a second position to cam saidcover to the fully closed position, interlocking means, said manuallyoperable cam means being movable from said second position to said firstposition to permit opening of said cover during which movement saidinterlocking means is operated to prevent a closing operation of saidexternal operating handle, means operable when said manually operablecam means is in said first position to defeat said interlocking means topermit a closing operation of said operating handle, and saidinterlocking means automatically moving to a position to permit aclosing operation of said operating handle when said manually operablecam means is moved from said first position to said second position tocam said cover to said fully closed position.

4. In combination, an enclosure comprising a cabinet the front of whichis defined as having a top a bottom and two sides, said cabinet having afixed portion at one side of the front thereof, an openable coverpositioned at the front of said cabinet, a circuit interrupter mountedinside of said enclosure and having an operating member operable to openand close said interrupter, an external operating handle extending fromsaid fixed front portion, means operatively connecting said externaloperating handle to said operating member in such a manner that saidoperative connection is maintained regardless of the position of saidcover, a cover latching mechanism, a gasket, said cover latchingmechanism comprising manually operable cam means operable from outsideof said enclosure, said manually operable cam means being movable froman unlatching position to a latching position to force said cover to afully closed latched position in which fully closed latched positionsaid gasket is compressed between said cover and said cabinet,interlocking means operating automatically to prevent closing of saidcircuit interrupter when said manually operable cam means is moved fromsaid latching position to said unlatching position to permit opening ofsaid cover, said interlocking means automatically engaging said manuallyoperable cam means to prevent opening of said cover when said cover isin said fully closed position and said manually operable cam means is insaid latching position, and means operable from outside of saidenclosure when said manually operable cam means is in said latchingposition and said cover is in said fully closed position to defeat saidinterlocking means to permit opening of said cover.

5. In combination, an enclosure comprising a cabinet the front of whichis defined as having a top a bottom and two sides, said cabinet having afixed portion at one side of the front thereof, an openable coverpositioned at the front of said cabinet, a circuit interrupter mountedinside of said enclosure and having an operating member operable to openand close said interrupter, an external operating 'handle extending fromsaid fixed front portion and being movable in a plane that is generallynormal to the plane defined by the plane of the front of said cover whensaid cover is in a fully closed position, means operatively connectingsaid external operating handle to said operating member in such a mannerthat said operative connection is maintained regardless of the positionof said cover, a cover latching mechanism, a gasket, said cover latchingmechanism comprising manually operable cam means being operable fromoutside of said enclosure, said manually operable cam means beingoperable from a first position to a second position to force said coverto the fully closed position in which fully closed position said gasketis compressed between said cover and said cabinet, interlocking means,said manually operable cam means being operable from said secondposition to said first position to release said cover from said fullyclosed position during which movement said interlocking means isoperated to prevent a closing operation of said external operatinghandle, and means operable when said manually operable cam means isoperated to said first position to defeat said interlocking means topermit a closing operation of said operating handle.

6. In combination, an enclosure comprising a cabinet having a fixedportion at the front thereof, an openable cover positioned at the "frontof said cabinet, a circuit interrupter mounted inside of said enclosureand having an operating member operable to open and close saidinterrupter, an external operating handle extending from said fixedportion and being movable in a plane generally normal to the planedefined by the front of said cover when said cover is in a fully closedposition, means operatively connecting said external operating handle tosaid operating member in such a manner that said operative connection ismaintained regardless of the position of said cover, a cover latchingmechanism, a gasket, said cover latching mechanism comprising manuallyoperable cam means operable from outside of said enclosure, saidmanually operable cam means being movable from a first position to asecond position to force said cover to the fully closed position inwhich fully closed position said gasket is compressed between said coverand said cabinet, interlocking means, said manually operable cam meansbeing movable from said second position to said first position to permitopening of said cover during which movement said interlocking means isoperated to prevent a closing operation of said external operatinghandle, means operable when said manually operable cam means is in saidfirst position to defeat said interlocking means to permit a closingoperation of said operating handle, and said interlocking meansautomatically moving to a position to permit a closing operation of saidoperating handle when said manually operable cam means is moved fromsaid first position to said second position to move said cover to saidfully closed position.

7. In combination, an enclosure comprising a cabinet the front of whichis defined as having a top a bottom and two sides, said cabinet having afixed portion at one side of the front thereof, an openable coverpositioned at the front of said cabinet, a circuit interrupter mountedinside of said enclosure and having an operating member operable to openand close said interrupter, an external operating handle extending fromsaid fixed front portion to move in a plane generally normal to theplane defined by the front of said cover when said cover is in a fullyclosed position, means operatively connecting said external operatinghandle to said operating member in such a manner that said operativeconnection is maintained regardless of the position of said cover, acover latching mechanism, a gasket, said cover latching mechanismcomprising manually operable cam means operable from outside of saidenclosure, said manually operable cam means being movable from a firstposition to a second position to cam said cover to the fully closedposition in which fully closed position said gasket is compressedbetween said cover and said cabinet, interlocking means, said manuallyoperable cam means being movable from said second position to said firstposition to release said cover from said fully closed position duringwhich movement said interlocking means is operated to prevent a closingoperating of said external operating handle, means operable when saidmanually operable cam means is in said first position to defeat saidinterlocking means to permit a closing operation of said operatinghandle, and said interlocking means automatically moving to a positionto permit a closing operation of said operating handle when saidmanually operable cam means is moved rom said first position to saidsecond position to cam said cover to said fully closed position.

8. In combination, an enclosure comprising a cabinet the front of whichis defined as having a top, a bottom and two sides, said cabinet havinga fixed portion at one side of the front thereof, an openable coverpositioned at the front of said cabinet, a circuit interrupter mountedinside of said enclosure and having an operating member operable to openand close said interrupter, an external operating handle extending fromsaid fixed portion, means operatively connecting said external operatinghandle to said operating member in such a manner that said operativeconnection is maintained regardless of the position of said cover, acover latching mechanism, a gasket, said cabinet having a portionextending generally normal to the plane of said cover, said coverlatching mechanism comprising manually operable cam means operable fromoutside of said enclosure, said manually operable cam means beingoperable from a first position to a second position to force said coverto a fully closed position in which fully closed position said gasket iscompressed between said generally normal portion of said cabinet andsaid cover, interlocking means, said manually operable cam means beingoperable from said second position to said first position to releasesaid cover from said fully closed position during which operation saidinterlocking means is operated to prevent a closing operation of saidexternal operating handle, means operable when said manually operablecam means is in said first position to defeat said interlocking means topermit a closing operation of said operating handle, and saidinterlocking means automatically moving to a position to permit aclosing operation of said operating handle when said manually operablecam means is moved from said first position to said second position tomove said cover to said fully closed position.

9. In combination, an enclosure comprising a cabinet having a fixedportion at the front thereof, an openable cover positioned at the frontof said cabinet, a circuit interrupter mounted inside of said enclosureand having an operating member operable to open and close saidinterrupter, an external operating handle extending from said fixedportion to move in a plane generally normal to the plane defined by thefront of said cover when said cover is in a fully closed position, meanscomprising reciprocable push rods operatively connecting said externaloperating handle to said operating member in such a manner that saidoperative connection is maintained regardless of the position of saidcover, a cover latching mechanism, .a gasket, said cover latchingmechanism comprising manually operable cam means movable from outside ofsaid enclosure from a first position to a second position to cam saidcover to the fully closed position in which fully closed position saidgasket is compressed between said cover and said cabinet, interlockingmeans, said manually operable cam means being movable from said secondposition to said first position to release said cover from said fullyclosed position during which movement said interlocking means isautomatically operated to prevent a closing operation of said externaloperating handle, and means operable when said manually operable cammeans is in said first position to defeat said interlocking means topermit a closing operation of said operating handle.

10. In combination, an enclosure comprising a cabinet the front of whichis defined as having a top a bottom and two sides, said cabinet having afixed portion at one side of the front thereof, an openable coverpositioned at the front of said cabinet, a circuit interrupter mountedinside of said enclosure and having an operating member operable to openand close said interrupter, an external operating handle extending fromsaid fixed front portion and being movable in a plane that is generallynormal to the plane defined by the front of said cover when said coveris in a fully closed position, means operatively connecting saidexternal operating handle to said operating member in such a manner thatsaid operative connection is maintained regardless of the position ofsaid cover, a cover latching mechanism, a gasket, said cabinet having aportion extending generally normal to the plane defined by the front ofsaid cover when said cover is in the fully closed position, manuallyoperable cam means operable from outside of said enclosure, saidmanually operable cam means being operable from a first position to asecond position to cam said cover to the fully closed position in whichfully closed position said gasket is compressed between said generallynormal portion of said cabinet and said cover, interlocking means, saidmanually operable cam means being operable from said second position tosaid first position to release said cover from said fully closedposition during which operation said interlocking means is automaticallypositioned to prevent a closing operation of said external operatinghandle, means operable when said manually operable cam means is in saidfirst position to defeat said interlocking means to permit a closingoperation of said operating handle, and said interlocking meansautomatically moving to a position to permit a closing operation of saidoperating handle when said manually operable cam means is moved fromsaid first position to said secend position to cam said cover to saidfully closed position.

References Cited in the file of this patent UNITED STATES PATENTS

1. IN COMBINATION, AN ENCLOSURE COMPRISING A CABINET THE FRONT OF WHICHIS DEFINED AS HAVING A TOP A BOTTOM AND TWO SIDES, A FIXED FRONT PORTIONAT ONE SIDE OF THE FRONT OF SAID CABINET, AN OPERABLE COVER POSITIONEDAT THE FRONT OF SAID CABINET, A CIRCUIT INTERRUPTER MOUNTED INSIDE OFSAID ENCLOSURE AND HAVING AN OPERATING MEMBER OPERABLE TO OPEN AND CLOSESAID INTERRUPTER, AN EXTERNAL OPERATING HANDLE EXTENDING FROM SAID FIXEDFRONT PORTION, MEANS OPERATIVELY CONNECTING SAID EXTERNAL OPERATINGHANDLE TO SAID OPERATING MEMBER IN SUCH A MANNER THAT SAID OPERATIVECONNECTION IS MAINTAINED REGARDLESS OF THE POSITION OF SAID COVER, ACOVER LATCHING MECHANISM COMPRISING MANUALLY OPERABLE CAM MEANS OPERABLEFROM OUTSIDE OF SAID ENCLOSURE AND BEING OPERABLE FROM AN UNLATCHINGPOSITION TO A LATCHING POSITION TO CAM SAID COVER TO A FULLY CLOSEDLATCHED POSITION, INTERLOCKING MEANS OPERATING TO PREVENT CLOSING OFSAID CIRCUIT INTERRUPTER WHEN SAID CIRCUIT INTERRUPTER IS OPEN AND SAIDMANUALLY OPERABLE CAM MEANS IS MOVED FROM SAID LATCHING POSITION TO SAIDUNLATCHING POSITION TO PERMIT OPENING OF SAID COVER, SAID INTERLOCKINGMEANS ENGAGING SAID MANUALLY OPERABLE CAM MEANS TO PREVENT OPENING OFSAID COVER WHEN SAID COVER IS IN SAID FULLY CLOSED LATCHED POSITION ANDSAID MANUALLY OPERABLE CAM MEANS IS IN SAID LATCHING POSITION, MEANSOPERABLE FROM OUTSIDE OF SAID ENCLOSURE WHEN SAID MANUALLY OPERABLE CAMMEANS IS IN SAID LATCHING POSITION AND SAID COVER IS IN SAID FULLYCLOSED POSITION TO DEFEAT SAID INTERLOCKING MEANS TO PERMIT OPENING OFSAID COVER.